New Study Links Shingles to Cognitive Decline

Research published on Tuesday is the latest to suggest that the viral disease shingles can be harmful to our long-term brain health. Scientists have shown that people who have had shingles were about 20% more likely to experience cognitive decline afterwards. The findings appear to bolster the growing idea that the shingles vaccine can be protective against dementia.

Shingles is caused by the varicella zoster virus (VSV), the same germ that causes chickenpox in children and younger adults. After someone recovers from chickenpox, the virus will often manage to survive and hide dormant inside our nervous system. Years, usually decades later, about one-third of chickenpox cases will experience a resurgent infection of the virus, known as shingles. Shingles is no picnic, often causing excruciating pain, rashes, and other symptoms for up to five weeks. Some people will also develop lingering nerve pain that can last for years.

Some research has suggested that VSV and other germs hiding in the brain can cause subtle neurological harm, particularly an increased risk of Alzheimer’s disease and dementia. But this remains contentious and some studies have failed to support such a connection. Scientists at Brigham and Women’s Hospital led this newest study, hoping to better untangle any potential relationship between shingles and worsening brain health.

The researchers analyzed data from three earlier large-scale studies that have proactively tracked the long-term health of nursing and health care professionals (these are known as prospective studies). As part of these studies, people were regularly asked about their cognitive health and if they ever had shingles. Overall, nearly 150,000 people were included in their analysis.

Those who reported having shingles were noticeably more likely to report having some cognitive decline, the researchers found. Even after accounting for other factors, they found that having shingles was associated with a 20% higher risk of subjective cognitive decline in men and women alike. The associated risk was higher in men who also carried the gene APOE4, a common genetic variation already known to raise Alzheimer’s risk. Their findings were published Tuesday in the journal Alzheimer’s Research & Therapy.

This study alone cannot prove a causative link between shingles and cognitive decline, but it’s the latest piece of evidence to support it. In late July, for instance, scientists in the UK found that people given Shingrix, the newest available shingles vaccine, were less likely to develop dementia over a six year span, even when compared to people who were given an earlier, less potent shingles vaccine. Shingrix is already highly effective at its main job, providing upwards of 90% protection from shingles for at least seven years. The Brigham and Women’s Hospital team’s earlier research has also shown that shingles may raise the risk of long-term cardiovascular disease. So given that and these latest findings, the researchers say that preventing shingles might even be more worthwhile than currently thought.

“Our findings show long-term implications of shingles and highlight the importance of public health efforts to prevent and promote uptake of the shingles vaccine,” said researcher Sharon Curhan, an assistant professor of medicine at Brigham and Women’s Hospital, in a statement from the hospital. “Given the growing number of Americans at risk for this painful and often disabling disease and the availability of a very effective vaccine, shingles vaccination could provide a valuable opportunity to reduce the burden of shingles and possibly reduce the burden of subsequent cognitive decline.”

Because of how common chickenpox used to be, about one in three Americans over the age of 50 are expected to develop shingles in their lifetime without vaccination. So given how painful of a experience it can be, preventing shingles with two simple shots is an easy bargain to take—possibly keeping your brain sharper as you age is just a cherry on top.